#pragma once
#include<string>
using namespace std;
class SalesItem{
	public:
		SalesItem();
		virtual ~SalesItem();
		SalesItem& operator=(SalesItem&si);
		string isbn();
		friend ostream& operator<<(ostream& os,SalesItem&si);
		friend istream& operator>>(istream& is, SalesItem& si);
		SalesItem& combine(SalesItem& si);
		private:
		string _book_no;
		unsigned int _units_sold=0;
		double _selling_price=0.0;
		double _sale_price=0.0;
		double _discout=0.0;
	
};
